There are many different types of ammunition manufactured. To give just a few examples, there are tracer rounds, armor piercing incendiary rounds, high explosive rounds, and training rounds (and combinations of these and other types). It can be difficult to readily distinguish between different types of rounds simply from the appearance of the cartridge. Consequently, marking requirements are often put in place to allow those handling and using ammunition to quickly determine the type of round. Most commonly, this takes the form of colored paint applied to the tip of the bullet.
In the ammunition manufacturing process, bullet tip identification painting is ordinarily performed after the bullet is sealed into the case. While significant improvements have been made in the rate at which cartridges can be assembled (for instance, using automatic sealing systems like those offered by Hernon Manufacturing, Inc.), the application of paint to the bullet tip has remained a relatively slow, batch process.
Generally, a group of cartridges is held with bullet tips facing down and dipped in a container of paint to a predetermined depth. The paint must then be allowed to dry before the cartridges can be packaged. Where the type of cartridge dictates multiple color bands on the tip, the delay is correspondingly multiplied. The color band most distant from the tip is applied first, with the cartridges being dipped to a greater depth in this color. After drying, the cartridges are dipped to a shallower depth in the next color, which must then also dry. If a third color is needed, a third iteration of this must occur.
Thus, while equipment exists to allow the filling, assembling and sealing of cartridges at a rapid pace, bullet tip identification painting can often be a choke point for ammunition throughput.